The present invention relates to a railway car, and especially to reducing the noise in the passenger cabin of a railway car moving at a high speed.
Heretofore, the vibration of the passenger cabin is reduced by providing a rubber vibration isolator between the car body and the floor of the cabin, thereby reducing the noise generated within the body of the railway car. Further, a damping material is adhered to the car body to provide the same effect.
The structure of the car body will now be explained. The car body comprises an underframe, side framing, roof framing, and buffer beams positioned at the longitudinal ends of the body. The floor is mounted on plural common joists placed on the underframe. On the lower surface of the underframe is positioned a member for connecting the body to a truck or bogie. This member is positioned on a bolster mounted on the width direction of the underframe. Center sills are positioned in the front and back areas of the bolster. The rigidity of these beams is relatively high. Further, the rigidity of the underframe and the common joists is also relatively high. The vibration generated in the truck is transmitted to the connection member, the underframe, the common joists and the floor in this order by solid-state transmission, causing noise inside the passenger cabin. This vibration is generally between 100 to 300 Hz.
Studies of the solid-state transmission discovered that the vibration of the truck is transmitted to the underframe. The floor is fixed onto the underframe via common joists. The floor is fixed firmly onto the underframe via common joists. The rigidity of the underframe and the common joists is relatively high. Therefore, the noise generated within the passenger cabin is also high.
Especially, the connecting portion between the truck and the underframe has a relatively high rigidity due to the bolster and the center sill. The relation between the floor near the connecting portion and the underframe is similar to the relation between other members. Therefore, the noise from this connecting portion is relatively large.
The object of the present invention is to reduce the noise generated at the connecting portion between the car body and the truck.
In order to achieve the above object, the present invention provides a railway car comprising two side sills, a base plate positioned between said two side sills, a bolster positioned under said base plate between said two side sills, a center sill connected to said bolster, a plurality of common joists mounted above said base plate, and a floor of a passenger cabin mounted on said common joists, wherein the common joists are characterized in that in the longitudinal end portion of said car body beyond said bolster, the common joists exist at the width-direction-ends of said car body but no common joists exist in the center of width of said car body.